I have an unusual use case where Zotero's behavior has recently changed, during late December.

Zotero automatically replaces hyphens in a page range with an en-dash. However, this only occurs with a simple page range such as 1–2. With a complex page range such as 1-2,4-5 that replacement does not occur. I like to use complex page ranges like that in some of my research (I realize that is unusual). My workaround for consistency was manually typing an en-dash in those complex page ranges when entering the locator in the Zotero pop up, and that worked fine.

Between Dec 18 and Dec 30 (based on saved drafts), something changed. Now Zotero actually replaces those manually-entered en-dashes with hyphens, so that there is, as far as I can tell, no way to make this consistent. I understand why Zotero replaces hyphens (easier to type) with en-dashes (proper formatting) and why it doesn't do it for complex page ranges (rare use case, and hard to automatically identifying the patterns), but I don't see why en-dashes should ever be replaced by hyphens.